scholarly journals Self-healing concrete-What Is it Good For?

2021 ◽  
Vol 71 (341) ◽  
pp. e237
Author(s):  
M. Roig-Flores ◽  
S. Formagini ◽  
P. Serna
Keyword(s):  
Sodium Silicate ◽  
Critical Discussion ◽  
Natural Process ◽  
Self Healing ◽  
Vascular Networks ◽  
Superabsorbent Polymers ◽  
Basic Concepts ◽  
Good For ◽  
Concrete Matrix

Self-healing of concrete is the process in which the material regenerates itself repairing inner cracks. This process can be produced by autogenous or autonomous healing. Autogenous healing is a natural process, produced by carbonation and/or continuing hydration. Autonomous healing is based on the use of specific agents to produce self-healing, which can be added directly to the concrete matrix, embedded in capsules or introduced through vascular networks. Some examples are superabsorbent polymers, crystalline admixtures, microencapsulated sodium silicate, and bacteria. This review is structured into two parts. The first part is an overview of self-healing concrete that summarises the basic concepts and the main advances produced in the last years. The second part is a critical discussion on the feasibility of self-healing concrete, its possibilities, current weaknesses, and challenges that need to be addressed in the coming years.

scholarly journals Rapid synchronized fabrication of vascularized thermosets and composites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mayank Garg ◽  
Jia En Aw ◽  
Xiang Zhang ◽  
Polette J. Centellas ◽  
Leon M. Dean ◽  
...  
Keyword(s):  
Large Scale ◽  
Capillary Flow ◽  
External Heat ◽  
Frontal Polymerization ◽  
Self Healing ◽  
Vascular Networks ◽  
Ambient Conditions ◽  
External Energy ◽  
Imaging Phantoms ◽  
Vascular Structures

AbstractBioinspired vascular networks transport heat and mass in hydrogels, microfluidic devices, self-healing and self-cooling structures, filters, and flow batteries. Lengthy, multistep fabrication processes involving solvents, external heat, and vacuum hinder large-scale application of vascular networks in structural materials. Here, we report the rapid (seconds to minutes), scalable, and synchronized fabrication of vascular thermosets and fiber-reinforced composites under ambient conditions. The exothermic frontal polymerization (FP) of a liquid or gelled resin facilitates coordinated depolymerization of an embedded sacrificial template to create host structures with high-fidelity interconnected microchannels. The chemical energy released during matrix polymerization eliminates the need for a sustained external heat source and greatly reduces external energy consumption for processing. Programming the rate of depolymerization of the sacrificial thermoplastic to match the kinetics of FP has the potential to significantly expedite the fabrication of vascular structures with extended lifetimes, microreactors, and imaging phantoms for understanding capillary flow in biological systems.

scholarly journals The Effect of Superabsorbent Polymers on the Microstructure and Self-Healing Properties of Cementitious-Based Composite Materials

2021 ◽  
Vol 11 (2) ◽  
pp. 700
Author(s):  
Irene A. Kanellopoulou ◽  
Ioannis A. Kartsonakis ◽  
Costas A. Charitidis
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Hybrid Structure ◽  
The Self ◽  
Self Healing ◽  
Cementitious Composite ◽  
Superabsorbent Polymers ◽  
Porosity Reduction ◽  
Environment Control ◽  
The Impact

Cementitious structures have prevailed worldwide and are expected to exhibit further growth in the future. Nevertheless, cement cracking is an issue that needs to be addressed in order to enhance structure durability and sustainability especially when exposed to aggressive environments. The purpose of this work was to examine the impact of the Superabsorbent Polymers (SAPs) incorporation into cementitious composite materials (mortars) with respect to their structure (hybrid structure consisting of organic core—inorganic shell) and evaluate the microstructure and self-healing properties of the obtained mortars. The applied SAPs were tailored to maintain their functionality in the cementitious environment. Control and mortar/SAPs specimens with two different SAPs concentrations (1 and 2% bwoc) were molded and their mechanical properties were determined according to EN 196-1, while their microstructure and self-healing behavior were evaluated via microCT. Compressive strength, a key property for mortars, which often degrades with SAPs incorporation, in this work, practically remained intact for all specimens. This is coherent with the porosity reduction and the narrower range of pore size distribution for the mortar/SAPs specimens as determined via microCT. Moreover, the self-healing behavior of mortar-SAPs specimens was enhanced up to 60% compared to control specimens. Conclusively, the overall SAPs functionality in cementitious-based materials was optimized.

scholarly journals Influencing Factors on the Healing Performance of Microcapsule Self-Healing Concrete

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4139
Author(s):  
Yanju Wang ◽  
Zhiyang Lin ◽  
Can Tang ◽  
Wenfeng Hao
Keyword(s):  
Compressive Strength ◽  
Sodium Silicate ◽  
Recovery Rate ◽  
Sound Speed ◽  
Orthogonal Experimental Design ◽  
Self Healing ◽  
Damage Degree ◽  
Strength Recovery ◽  
Healing System ◽  
Recovery Performance

The amounts of the components in a microcapsule self-healing system significantly impact the basic performance and self-healing performance of concrete. In this paper, an orthogonal experimental design is used to investigate the healing performance of microcapsule self-healing concrete under different pre-damage loads. The strength recovery performance and sound speed recovery performance under extensive damage are analyzed. The optimum factor combination of the microcapsule self-healing concrete is obtained. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are carried out on the concrete samples before and after healing to determine the healing mechanism. The results show that the healing effect of self-healing concrete decreases with an increase in the pre-damage load, and the sound speed recovery rate increases with an increase in the damage degree. The influence of the sodium silicate content on the compressive strength and compressive strength recovery rate of the self-healing concrete increases, followed by a decrease. The optimum combination of factors of the microcapsule self-healing system is 3% microcapsules, 30% sodium silicate, and 15% sodium fluosilicate. The results can be used for the design and preparation of self-healing concrete.

scholarly journals Development of 3D Printed Networks in Self-Healing Concrete

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1328 ◽  
Author(s):  
Cristina De Nardi ◽  
Diane Gardner ◽  
Anthony Duncan Jefferson
Keyword(s):  
Vascular System ◽  
Physical And Mechanical Properties ◽  
Self Healing ◽  
Vascular Networks ◽  
Minimal Impact ◽  
Cementitious Matrix ◽  
Healing Agent ◽  
3D Printed ◽  
Series Of Experiments ◽  
Concrete Elements

This paper presents a new form of biomimetic cementitious material, which employs 3D-printed tetrahedral mini-vascular networks (MVNs) to store and deliver healing agents to damage sites within cementitious matrices. The MVNs are required to not only protect the healing agent for a sufficient period of time but also survive the mixing process, release the healing agent when the cementitious matrix is damaged, and have minimal impact on the physical and mechanical properties of the host cementitious matrix. A systematic study is described which fulfilled these design requirements and determined the most appropriate form and material for the MVNs. A subsequent series of experiments showed that MVNs filled with sodium silicate, embedded in concrete specimens, are able to respond effectively to damage, behave as a perfusable vascular system and thus act as healing agent reservoirs that are available for multiple damage-healing events. It was also proved that healing agents encapsulated within these MVNs can be transported to cracked zones in concrete elements under capillary driving action, and produce a recovery of strength, stiffness and fracture energy.

scholarly journals Mechanisms of encapsulation of bacteria in self-healing concrete: review

DYNA ◽  
2019 ◽  
Vol 86 (210) ◽  
pp. 17-22
Author(s):  
Martín Eduardo Espitia Nery ◽  
Dery Esmeralda Corredor Pulido ◽  
Paula Andrea Castaño Oliveros ◽  
Johan Andrey Rodriguez Medina ◽  
Querly Yubiana Ordoñez Bello ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Concrete Strength ◽  
Self Healing ◽  
Bacterial Survival ◽  
Precipitate Calcium Carbonate ◽  
Structural Deterioration ◽  
Bacterial Encapsulation ◽  
Concrete Matrix ◽  
In Situ Repair

Fissures in concrete structures result from structural deterioration and inadequate building processes, among other factors. Traditional in situ repair is often expensive and complex. For this reason, self-healing techniques have been developed, such as the use of bacteria that precipitate calcium carbonate and seal fissures. However, adding bacteria directly to the concrete matrix reduces bacterial survival. We present a review of different methods of bacterial encapsulation and their effects on fissure repair and concrete resistance. We argue that encapsulation of Bacillus subtilis in clay is the most promising method for this type of concrete, increasing concrete strength by 12% and repairing fissures of up to 0.52 mm.

scholarly journals The Influence of Superabsorbent Polymers and Nanosilica on the Hydration Process and Microstructure of Cementitious Mixtures

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5194
Author(s):  
Gerlinde Lefever ◽  
Dimitrios G. Aggelis ◽  
Nele De Belie ◽  
Marc Raes ◽  
Tom Hauffman ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Isothermal Calorimetry ◽  
Autogenous Shrinkage ◽  
Hydration Process ◽  
Microstructural Development ◽  
Self Healing ◽  
Hydration Kinetics ◽  
Superabsorbent Polymers ◽  
Water To Cement Ratio ◽  
Supplementary Material

Superabsorbent polymers (SAPs) are known to mitigate the development of autogenous shrinkage in cementitious mixtures with a low water-to-cement ratio. Moreover, the addition of SAPs promotes the self-healing ability of cracks. A drawback of using SAPs lies in the formation of macropores when the polymers release their absorbed water, leading to a reduction of the mechanical properties. Therefore, a supplementary material was introduced together with SAPs, being nanosilica, in order to obtain an identical compressive strength with respect to the reference material without additives. The exact cause of the similar compressive behaviour lies in the modification of the hydration process and subsequent microstructural development by both SAPs and nanosilica. Within the present study, the effect of SAPs and nanosilica on the hydration progress and the hardened properties is assessed. By means of isothermal calorimetry, the hydration kinetics were monitored. Subsequently, the quantity of hydration products formed was determined by thermogravimetric analysis and scanning electron microscopy, revealing an increased amount of hydrates for both SAP and nanosilica blends. An assessment of the pore size distribution was made using mercury intrusion porosimetry and demonstrated the increased porosity for SAP mixtures. A correlation between microstructure and the compressive strength displayed its influence on the mechanical behaviour.

Evaluation of Self-Healing Mechanisms in Concrete with Double-Walled Sodium Silicate Microcapsules

2015 ◽  
Vol 27 (12) ◽  
pp. 04015035 ◽  
Author(s):  
Ehsan Mostavi ◽  
Somayeh Asadi ◽  
Marwa M. Hassan ◽  
Mohamed Alansari
Keyword(s):  
Sodium Silicate ◽  
Self Healing

Influence of triethanolamine on reactivity of hydrated matrix in sodium silicate self-healing system and the mechanism

2018 ◽  
Vol 185 ◽  
pp. 445-452 ◽  
Author(s):  
Miaomiao Hu ◽  
Jintang Guo ◽  
Yang Xu ◽  
Jinjie Fan ◽  
Lei Cao ◽  
...  
Keyword(s):  
Sodium Silicate ◽  
Self Healing ◽  
Healing System

scholarly journals Superabsorbent polymers to seal and heal cracks in cementitious materials

2018 ◽  
Vol 3 ◽  
pp. 32-38 ◽  
Author(s):  
Didier Snoeck
Keyword(s):  
Crack Width ◽  
Autogenous Shrinkage ◽  
Building Blocks ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Current Status ◽  
Self Healing ◽  
Superabsorbent Polymers ◽  
Concrete Cracking ◽  
Freeze Thaw

Superabsorbent polymers (SAPs) are promising admixtures to improve properties in cementitious materials. Not only useful to mitigate autogenous shrinkage and to increase the freeze-thaw resistance, SAP particles may enhance self-sealing and self-healing in cementitious materials. The self-sealing leads to a regain in water tightness and promoted autogenous healing may prove to be useful to limit repair works caused by concrete cracking. By providing sufficient building blocks for healing, limiting the crack width by means of synthetic microfibers and inducing water by means of SAPs, a smart cementitious material is obtained. This material can be an excellent material to use in future building applications such as tunnel works and ground-retaining structures. This paper gives an overview of the current status of the research on SAPs in cementitious materials to obtain sealing and healing.

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